docs: def setting(self, opt, val):
          """change an arbitrary synth setting, type-smart"""
          opt = opt.encode()
          if isinstance(val, basestring):
              fluid_settings_setstr(self.settings, opt, val)
          elif isinstance(val, int):
              fluid_settings_setint(self.settings, opt, val)
          elif isinstance(val, float):
              fluid_settings_setnum(self.settings, opt, val)